Load capacity and life

The basic static load rating as defined in ISO 76:1987 corresponds to a calculated contact stress at the centre of the most heavily loaded rolling element/raceway contact.

The basic dynamic load ratings for SKF bearings are determined in accordance with the procedures outlined in ISO 281:1990. The load ratings given in this catalogue apply to chromium steel bearings, heat-treated to a minimum hardness of 58 HRC.

There are several types of bearing life. One of these is "service life", which represents the actual life of a bearing in real operating conditions before it fails. Note that individual bearing life can only be predicted statistically. Life calculations refer only to a bearing population and a given degree of reliability, i.e. 90 %, furthermore field failures are not generally caused by fatigue, but are more often caused by contamination, wear, misalignment, corrosion, or as a result of cage, lubrication or seal failure.

Another type of life is the "specification life". This is the life specified by an authority, for example, based on hypothetical load and speed data supplied by the same authority. It is generally a requisite L10 basic rating life and based on experience gained from similar applications.